In recent years, elctroluminescent (EL) devices in both a thin-film EL type and a thick-film type have been suggested to display a multi-color image. Both of the thin-film and thick-film EL devices, however, are burdened with major shortcomings.
To be more specific, the thin-film EL device, while capable of providing a red light of a commercially acceptable brightness level, is incapable of providing the same for a blue light of a commercially acceptable brightness level, whereas the thick-film EL device, while capable of providing a blue light of a commercially acceptable brightness level, is incapable of providing the same for a red light of a commercially acceptable brightness level.
In other words, neither the thin-film EL device nor the thick-film EL device could provide the blue light and red lights of a commercially acceptable brightness level concurrently to thereby prevent the EL devices from displaying a full-color image of a commercially acceptable brightness level.